Self-Cleaning Well Control Fluid Using Decomposable Solids
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Solution Overview
Problem
Existing well control methods, such as viscosifying kill fluids with solids, often damage wells and formations, and require additional steps for cleanup, especially after hydraulic fracturing, as these solids can be difficult to remove and may invade fractures or formations.
Innovation Solution
A method involving a slurry of gelled viscoelastic surfactant fluid combined with a decomposable first solid, which forms a plug to prevent fluid flow and then decomposes, allowing the fluid to break without the need for additional chemicals or tools, using pH control agents to maintain stability and control decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solids and viscosifiers are added to kill fluid to prevent fluid flow, then well control effectiveness is improved, but well damage and formation damage occur
Solution Approach 1:
The invention changes the chemical parameters of the kill fluid by using viscoelastic surfactants that can dramatically increase viscosity under specific conditions (high salt concentration, high temperature) while remaining fluid under other conditions. This allows the fluid to be pumpable during injection but highly viscous for well control during static periods, eliminating the need for damaging solids and viscosifiers.
Solution Approach 2:
The invention creates a composite system combining viscoelastic surfactant, salt (NaCl), and water that exhibits non-Newtonian rheological properties. The composite material transitions from low viscosity during pumping to high viscosity during static periods, providing effective well control without the damage associated with traditional solids-based systems.
2Reliability
If traditional kill fluids with solids are used to control well flow, then fluid flow prevention is improved, but additional cleanup steps are required
Solution Approach 1:
The kill fluid system is designed to be self-cleaning. The viscoelastic surfactant naturally breaks down after providing well control, and the high salt concentration prevents formation damage. No additional chemicals, tools, or mechanical intervention are required to remove the fluid or solids, as the system self-dissipates harmlessly.
Solution Approach 2:
The invention extracts the harmful solids and complex viscosifiers from the kill fluid system, replacing them with a salt-based viscoelastic surfactant system that provides the same well control function without requiring removal or cleanup operations.
3Duration of action of moving object
If delay agents are used to prevent premature breakdown of viscoelastic surfactant, then well control duration is improved, but device complexity and cost increase
Solution Approach 1:
The invention creates a dynamic system where the viscosity of the kill fluid changes over time based on environmental conditions. The viscoelastic surfactant naturally maintains high viscosity during the well control period and then breaks down when conditions change (e.g., when exposed to produced fluids or after a predetermined time), eliminating the need for complex delay agents or triggered breakdown mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents fluid flow without damaging the well or formation, allowing for non-damaging well control that does not require subsequent cleanup, as the decomposable solids and surfactant fluid spontaneously decompose into non-damaging products, maintaining well integrity and reducing operational complexity.
Implementation Method 1
The well control fluid is also commonly viscosified to reduce flow
Implementation Method 2
the first solid to decompose and the viscoelastic surfactant fluid to break
Data Source
AI summary
A composition and method is given for a well control fluid that is injected into a well during completion or remediation and prevents fluid flow from a formation into the well during operations (such as shut-in, or placement or adjustment of tools/hardware) when no fluid flow is desired. The composition includes a viscoelastic surfactant fluid system (VES) and a decomposable first solid material, preferably in fiber form, that forms a pack or plug in the well at the location where fluid would otherwise leak off, and then decomposes without intervention to release a product that is a breaker for the surfactant or the micelles of the VES. The composition optionally also contains a pH control agent and a second solid (that may also be a fluid loss agent) that affect the decomposition of the first solid.